Gravatar link generator. Please refer: https://en.gravatar.com/site/implement

rubyrails.rb

# require 'digest/md5'

def gravatar_link(email, size=80)
  valid_email = /^([a-zA-Z0-9_\-\.]+)@([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5})$/                                                                           
  raise 'Invalid email address' unless !!email.match(valid_email)                              
  raise 'Invalid gravatar image size' unless size.positive? && size < 2048
  hash = Digest::MD5.hexdigest(email.downcase)
  "https://www.gravatar.com/avatar/#{hash}?s=#{size}"
end

def gravatar_profile(email, json = false)
  valid_email = /^([a-zA-Z0-9_\-\.]+)@([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5})$/                                                                           
  raise 'Invalid email address' unless !!email.match(valid_email)      
  hash = Digest::MD5.hexdigest(email.downcase)
  "https://www.gravatar.com/#{hash}#{json ? '.json' : ''}"
end